469 lines
13 KiB
Python
469 lines
13 KiB
Python
# Original bencode module by Petru Paler, et al.
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#
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# Modifications by Connelly Barnes:
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#
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# - Added support for floats (sent as 32-bit or 64-bit in network
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# order), bools, None.
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# - Allowed dict keys to be of any serializable type.
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# - Lists/tuples are always decoded as tuples (thus, tuples can be
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# used as dict keys).
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# - Embedded extra information in the 'typecodes' to save some space.
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# - Added a restriction on integer length, so that malicious hosts
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# cannot pass us large integers which take a long time to decode.
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#
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# Licensed by Bram Cohen under the "MIT license":
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#
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# "Copyright (C) 2001-2002 Bram Cohen
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#
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# Permission is hereby granted, free of charge, to any person
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# obtaining a copy of this software and associated documentation files
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# (the "Software"), to deal in the Software without restriction,
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# including without limitation the rights to use, copy, modify, merge,
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# publish, distribute, sublicense, and/or sell copies of the Software,
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# and to permit persons to whom the Software is furnished to do so,
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# subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be
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# included in all copies or substantial portions of the Software.
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#
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# The Software is provided "AS IS", without warranty of any kind,
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# express or implied, including but not limited to the warranties of
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# merchantability, fitness for a particular purpose and
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# noninfringement. In no event shall the authors or copyright holders
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# be liable for any claim, damages or other liability, whether in an
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# action of contract, tort or otherwise, arising from, out of or in
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# connection with the Software or the use or other dealings in the
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# Software."
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#
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# (The rencode module is licensed under the above license as well).
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#
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"""
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rencode -- Web safe object pickling/unpickling.
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Public domain, Connelly Barnes 2006-2007.
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The rencode module is a modified version of bencode from the
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BitTorrent project. For complex, heterogeneous data structures with
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many small elements, r-encodings take up significantly less space than
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b-encodings:
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>>> len(rencode.dumps({'a':0, 'b':[1,2], 'c':99}))
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13
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>>> len(bencode.bencode({'a':0, 'b':[1,2], 'c':99}))
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26
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The rencode format is not standardized, and may change with different
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rencode module versions, so you should check that you are using the
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same rencode version throughout your project.
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"""
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import struct
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import sys
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from threading import Lock
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__version__ = ('Python', 1, 0, 4)
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__all__ = ['dumps', 'loads']
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py3 = sys.version_info[0] >= 3
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if py3:
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long = int # pylint: disable=redefined-builtin
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unicode = str # pylint: disable=redefined-builtin
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def int2byte(c):
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return bytes([c])
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else:
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def int2byte(c):
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return chr(c)
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# Default number of bits for serialized floats, either 32 or 64 (also a parameter for dumps()).
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DEFAULT_FLOAT_BITS = 32
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# Maximum length of integer when written as base 10 string.
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MAX_INT_LENGTH = 64
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# The bencode 'typecodes' such as i, d, etc have been extended and
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# relocated on the base-256 character set.
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CHR_LIST = int2byte(59)
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CHR_DICT = int2byte(60)
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CHR_INT = int2byte(61)
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CHR_INT1 = int2byte(62)
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CHR_INT2 = int2byte(63)
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CHR_INT4 = int2byte(64)
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CHR_INT8 = int2byte(65)
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CHR_FLOAT32 = int2byte(66)
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CHR_FLOAT64 = int2byte(44)
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CHR_TRUE = int2byte(67)
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CHR_FALSE = int2byte(68)
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CHR_NONE = int2byte(69)
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CHR_TERM = int2byte(127)
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# Positive integers with value embedded in typecode.
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INT_POS_FIXED_START = 0
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INT_POS_FIXED_COUNT = 44
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# Dictionaries with length embedded in typecode.
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DICT_FIXED_START = 102
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DICT_FIXED_COUNT = 25
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# Negative integers with value embedded in typecode.
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INT_NEG_FIXED_START = 70
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INT_NEG_FIXED_COUNT = 32
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# Strings with length embedded in typecode.
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STR_FIXED_START = 128
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STR_FIXED_COUNT = 64
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# Lists with length embedded in typecode.
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LIST_FIXED_START = STR_FIXED_START + STR_FIXED_COUNT
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LIST_FIXED_COUNT = 64
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# Whether strings should be decoded when loading
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_decode_utf8 = False
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def decode_int(x, f):
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f += 1
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newf = x.index(CHR_TERM, f)
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if newf - f >= MAX_INT_LENGTH:
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raise ValueError('overflow')
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try:
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n = int(x[f:newf])
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except (OverflowError, ValueError):
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n = long(x[f:newf])
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if x[f:f + 1] == '-':
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if x[f + 1:f + 2] == '0':
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raise ValueError
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elif x[f:f + 1] == '0' and newf != f + 1:
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raise ValueError
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return (n, newf + 1)
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def decode_intb(x, f):
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f += 1
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return (struct.unpack('!b', x[f:f + 1])[0], f + 1)
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def decode_inth(x, f):
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f += 1
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return (struct.unpack('!h', x[f:f + 2])[0], f + 2)
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def decode_intl(x, f):
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f += 1
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return (struct.unpack('!l', x[f:f + 4])[0], f + 4)
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def decode_intq(x, f):
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f += 1
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return (struct.unpack('!q', x[f:f + 8])[0], f + 8)
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def decode_float32(x, f):
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f += 1
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n = struct.unpack('!f', x[f:f + 4])[0]
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return (n, f + 4)
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def decode_float64(x, f):
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f += 1
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n = struct.unpack('!d', x[f:f + 8])[0]
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return (n, f + 8)
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def decode_string(x, f):
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colon = x.index(b':', f)
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try:
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n = int(x[f:colon])
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except (OverflowError, ValueError):
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n = long(x[f:colon])
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if x[f] == '0' and colon != f + 1:
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raise ValueError
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colon += 1
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s = x[colon:colon + n]
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if _decode_utf8:
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s = s.decode('utf8')
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return (s, colon + n)
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def decode_list(x, f):
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r, f = [], f + 1
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while x[f:f + 1] != CHR_TERM:
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v, f = decode_func[x[f:f + 1]](x, f)
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r.append(v)
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return (tuple(r), f + 1)
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def decode_dict(x, f):
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r, f = {}, f + 1
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while x[f:f + 1] != CHR_TERM:
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k, f = decode_func[x[f:f + 1]](x, f)
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r[k], f = decode_func[x[f:f + 1]](x, f)
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return (r, f + 1)
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def decode_true(x, f):
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return (True, f + 1)
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def decode_false(x, f):
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return (False, f + 1)
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def decode_none(x, f):
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return (None, f + 1)
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decode_func = {}
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decode_func[b'0'] = decode_string
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decode_func[b'1'] = decode_string
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decode_func[b'2'] = decode_string
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decode_func[b'3'] = decode_string
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decode_func[b'4'] = decode_string
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decode_func[b'5'] = decode_string
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decode_func[b'6'] = decode_string
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decode_func[b'7'] = decode_string
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decode_func[b'8'] = decode_string
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decode_func[b'9'] = decode_string
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decode_func[CHR_LIST] = decode_list
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decode_func[CHR_DICT] = decode_dict
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decode_func[CHR_INT] = decode_int
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decode_func[CHR_INT1] = decode_intb
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decode_func[CHR_INT2] = decode_inth
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decode_func[CHR_INT4] = decode_intl
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decode_func[CHR_INT8] = decode_intq
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decode_func[CHR_FLOAT32] = decode_float32
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decode_func[CHR_FLOAT64] = decode_float64
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decode_func[CHR_TRUE] = decode_true
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decode_func[CHR_FALSE] = decode_false
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decode_func[CHR_NONE] = decode_none
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def make_fixed_length_string_decoders():
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def make_decoder(slen):
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def f(x, f):
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s = x[f + 1:f + 1 + slen]
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if _decode_utf8:
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s = s.decode('utf8')
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return (s, f + 1 + slen)
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return f
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for i in range(STR_FIXED_COUNT):
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decode_func[int2byte(STR_FIXED_START + i)] = make_decoder(i)
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make_fixed_length_string_decoders()
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def make_fixed_length_list_decoders():
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def make_decoder(slen):
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def f(x, f):
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r, f = [], f + 1
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for _ in range(slen):
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v, f = decode_func[x[f:f + 1]](x, f)
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r.append(v)
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return (tuple(r), f)
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return f
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for i in range(LIST_FIXED_COUNT):
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decode_func[int2byte(LIST_FIXED_START + i)] = make_decoder(i)
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make_fixed_length_list_decoders()
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def make_fixed_length_int_decoders():
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def make_decoder(j):
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def f(x, f):
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return (j, f + 1)
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return f
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for i in range(INT_POS_FIXED_COUNT):
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decode_func[int2byte(INT_POS_FIXED_START + i)] = make_decoder(i)
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for i in range(INT_NEG_FIXED_COUNT):
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decode_func[int2byte(INT_NEG_FIXED_START + i)] = make_decoder(-1 - i)
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make_fixed_length_int_decoders()
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def make_fixed_length_dict_decoders():
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def make_decoder(slen):
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def f(x, f):
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r, f = {}, f + 1
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for _ in range(slen):
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k, f = decode_func[x[f:f + 1]](x, f)
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r[k], f = decode_func[x[f:f + 1]](x, f)
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return (r, f)
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return f
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for i in range(DICT_FIXED_COUNT):
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decode_func[int2byte(DICT_FIXED_START + i)] = make_decoder(i)
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make_fixed_length_dict_decoders()
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def loads(x, decode_utf8=False):
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global _decode_utf8
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_decode_utf8 = decode_utf8
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try:
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r, l = decode_func[x[0:1]](x, 0)
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except (IndexError, KeyError):
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raise ValueError
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if l != len(x):
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raise ValueError
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return r
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def encode_int(x, r):
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if 0 <= x < INT_POS_FIXED_COUNT:
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r.append(int2byte(INT_POS_FIXED_START + x))
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elif -INT_NEG_FIXED_COUNT <= x < 0:
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r.append(int2byte(INT_NEG_FIXED_START - 1 - x))
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elif -128 <= x < 128:
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r.extend((CHR_INT1, struct.pack('!b', x)))
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elif -32768 <= x < 32768:
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r.extend((CHR_INT2, struct.pack('!h', x)))
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elif -2147483648 <= x < 2147483648:
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r.extend((CHR_INT4, struct.pack('!l', x)))
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elif -9223372036854775808 <= x < 9223372036854775808:
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r.extend((CHR_INT8, struct.pack('!q', x)))
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else:
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s = str(x)
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if py3:
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s = bytes(s, 'ascii')
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if len(s) >= MAX_INT_LENGTH:
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raise ValueError('overflow')
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r.extend((CHR_INT, s, CHR_TERM))
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def encode_float32(x, r):
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r.extend((CHR_FLOAT32, struct.pack('!f', x)))
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def encode_float64(x, r):
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r.extend((CHR_FLOAT64, struct.pack('!d', x)))
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def encode_bool(x, r):
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r.append({False: CHR_FALSE, True: CHR_TRUE}[bool(x)])
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def encode_none(x, r):
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r.append(CHR_NONE)
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def encode_string(x, r):
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if len(x) < STR_FIXED_COUNT:
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r.extend((int2byte(STR_FIXED_START + len(x)), x))
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else:
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s = str(len(x))
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if py3:
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s = bytes(s, 'ascii')
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r.extend((s, b':', x))
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def encode_unicode(x, r):
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encode_string(x.encode('utf8'), r)
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def encode_list(x, r):
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if len(x) < LIST_FIXED_COUNT:
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r.append(int2byte(LIST_FIXED_START + len(x)))
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for i in x:
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encode_func[type(i)](i, r)
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else:
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r.append(CHR_LIST)
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for i in x:
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encode_func[type(i)](i, r)
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r.append(CHR_TERM)
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def encode_dict(x, r):
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if len(x) < DICT_FIXED_COUNT:
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r.append(int2byte(DICT_FIXED_START + len(x)))
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for k, v in x.items():
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encode_func[type(k)](k, r)
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encode_func[type(v)](v, r)
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else:
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r.append(CHR_DICT)
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for k, v in x.items():
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encode_func[type(k)](k, r)
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encode_func[type(v)](v, r)
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r.append(CHR_TERM)
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encode_func = {}
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encode_func[int] = encode_int
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encode_func[long] = encode_int
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encode_func[bytes] = encode_string
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encode_func[list] = encode_list
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encode_func[tuple] = encode_list
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encode_func[dict] = encode_dict
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encode_func[type(None)] = encode_none
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encode_func[unicode] = encode_unicode
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encode_func[bool] = encode_bool
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lock = Lock()
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def dumps(x, float_bits=DEFAULT_FLOAT_BITS):
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"""
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Dump data structure to str.
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Here float_bits is either 32 or 64.
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"""
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with lock:
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if float_bits == 32:
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encode_func[float] = encode_float32
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elif float_bits == 64:
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encode_func[float] = encode_float64
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else:
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raise ValueError('Float bits (%d) is not 32 or 64' % float_bits)
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r = []
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encode_func[type(x)](x, r)
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return b''.join(r)
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def test():
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f1 = struct.unpack('!f', struct.pack('!f', 25.5))[0]
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f2 = struct.unpack('!f', struct.pack('!f', 29.3))[0]
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f3 = struct.unpack('!f', struct.pack('!f', -0.6))[0]
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ld = (({b'a': 15, b'bb': f1, b'ccc': f2, b'': (f3, (), False, True, b'')}, (b'a', 10**20),
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tuple(range(-100000, 100000)), b'b' * 31, b'b' * 62, b'b' * 64, 2**30, 2**33, 2**62,
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2**64, 2**30, 2**33, 2**62, 2**64, False, False, True, -1, 2, 0),)
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assert loads(dumps(ld)) == ld
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d = dict(zip(range(-100000, 100000), range(-100000, 100000)))
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d.update({b'a': 20, 20: 40, 40: 41, f1: f2, f2: f3, f3: False, False: True, True: False})
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ld = (d, {}, {5: 6}, {7: 7, True: 8}, {9: 10, 22: 39, 49: 50, 44: b''})
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assert loads(dumps(ld)) == ld
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ld = (b'', b'a' * 10, b'a' * 100, b'a' * 1000, b'a' * 10000, b'a' * 100000, b'a' * 1000000, b'a' * 10000000)
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assert loads(dumps(ld)) == ld
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ld = tuple([dict(zip(range(n), range(n))) for n in range(100)]) + (b'b',)
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assert loads(dumps(ld)) == ld
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ld = tuple([dict(zip(range(n), range(-n, 0))) for n in range(100)]) + (b'b',)
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assert loads(dumps(ld)) == ld
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ld = tuple([tuple(range(n)) for n in range(100)]) + (b'b',)
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assert loads(dumps(ld)) == ld
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ld = tuple([b'a' * n for n in range(1000)]) + (b'b',)
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assert loads(dumps(ld)) == ld
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ld = tuple([b'a' * n for n in range(1000)]) + (None, True, None)
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assert loads(dumps(ld)) == ld
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assert loads(dumps(None)) is None
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assert loads(dumps({None: None})) == {None: None}
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assert 1e-10 < abs(loads(dumps(1.1)) - 1.1) < 1e-6
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assert 1e-10 < abs(loads(dumps(1.1, 32)) - 1.1) < 1e-6
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assert abs(loads(dumps(1.1, 64)) - 1.1) < 1e-12
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assert loads(dumps('Hello World!!'), decode_utf8=True)
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try:
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import psyco
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psyco.bind(dumps)
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psyco.bind(loads)
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except ImportError:
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pass
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if __name__ == '__main__':
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test()
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